Many types of input devices are available for performing operations in a computing system, such as buttons or keys, mice, trackballs, joysticks, touch sensor panels, touch screens, and the like. Touch screens, in particular, are becoming increasingly popular because of their ease and versatility of operation as well as their declining price. Touch screens can include a touch sensor panel, which can be a clear panel with a touch-sensitive surface, and a display device such as a liquid crystal display (LCD) that can be positioned partially or fully behind the panel so that the touch-sensitive surface can cover at least a portion of the viewable area of the display device. Touch screens generally allow a user to perform various functions by touching (e.g., physical contact or near-field proximity) the touch sensor panel using a finger, stylus or other object at a location often dictated by a user interface (UI) being displayed by the display device.
Example touch screen input can include a scaling gesture, wherein a user touches a touch-sensitive surface with two fingers and pinches the fingers together or apart to scale an image on a screen. For example, a scaling gesture can be used to zoom in and out of a map in a mapping application. However, a user may be unable to perform a two finger gesture when attempting to hold and operate a device with only one hand.